Blender Git Loki

GPUViewport: Use GPUBatch for viewport drawing

When drawing the viewport to the screen the draw calls were not batched.
This resulted in measurable slowdown on Windows Intel 10th gen
platforms.

This patch would cache the last draw calls per viewport. Our API does
support partial redrawing of the viewport, but that isn't used anywhere.

This patch does not include stereoscopy rendering. This still uses the
imm approach and would still be slow on certain hardware.

Reviewed By: Cl�ment Foucault

Differential Revision: https://developer.blender.org/D7357